Segmental analysis of human hair reveals intra-annual variation in 25(OH)D3 concentrations in modern and archaeological individuals

The study examined 25(OH)D3 concentrations in human hair from 16 participants, including one archaeological individual, to assess vitamin D status. It found detectable levels in 14 participants, with significant intra-hair variability and higher concentrations in some linked to supplementation and weight loss. No significant trends were observed related to age, sex, BMI, supplement intake, outdoor time, or fish consumption. The research suggests hair analysis could provide time-series insights into vitamin D status, though further studies are needed due to the small sample size. The study also explored the potential of using hair analysis to assess historical vitamin D status, despite challenges like different extraction protocols and lack of ethnic diversity.